A variety of communication devices are known that operate in multiple frequency bands. For example, radiotelephones for operation in both the 900 MHz global system for mobile communications (GSM) standard and the 1.8 GHz digital cellular standard (DCS) specification in Europe are known. Dual band communication devices are also known to operate in the 800 MHz and 1.9 GHz frequency band in countries such as the United States of America.
In such communication devices, the receiver must provide adequate attenuation of signals outside of the receiver passbands. It is also necessary to separate signal paths for each of the passbands. Because the frequency bands are so far apart, the receive signals in the frequency band can be separated using a simple diplexer. Adequate attenuation is provided through the use of multiple filters. However as the number of passbands increases, the size and cost requirements of all of the filters increases detrimentally.
There is therefor a need for cost effective solutions for implementing receivers that operate in multiple frequency bands, as well as implementations that accommodate an increased number of frequency bands on smaller circuit boards and in smaller housings.